Structure-Function Correlation in Noise-Damaged Ears: A Light and Electron-Microscopic Study

Abstract

Of the roughly 50,000 afferent fibers in the cat’s auditory nerve, approximately 95% terminate peripherally on inner hair cells (IHCs), as the so-called “radial fibers” (RFs) [24,25]. RFs comprise the population of neurons sampled when the auditory nerve is impaled with glass microelectrodes [9]. In the cat, the great majority of RFs is unbranched, terminating on a single IHC via a single terminal swelling [24,8]. Thus, by sampling the activity of a single RF we have a window onto the functional state of a very restricted region of the organ of Corti. By sampling the activity of different single fibers, with different characteristic frequencies (CFs), we can assess the functional state of the entire cochlea, from base to apex.